Few diplomatic marriages are as hopelessly knotted -- or emotionally fraught -- as the one between Saudi Arabia and the United States. First joined in 1945 under an oil-for-security agreement, the two countries leaned on each other through the Cold War, the 1967 Six-Day War and the 1991 Persian Gulf War. The House of Saud provided welcome relief to President Jimmy Carter during the energy crisis in the '70s; later, Saudi mujaheddin were dispatched against Russian-occupied Afghanistan. Only after the attacks of Sept. 11, 2001, when it was discovered that 15 of the hijackers were Saudi nationals, did this "special relationship" -- always informal, never really defined -- begin to sour.

As former Washington Post reporter David B. Ottaway hints in his sweeping history, "The King's Messenger," it's a miracle the odd couple made it even that far. Saudi Arabia is "a secretive monarchy, Islamic theocracy, and Sunni monoculture," while the United States is a "religiously pluralistic society, wide-open democracy, and Babel of cultures," Ottaway writes. "Holding the alliance together was a delicate diplomatic task for both sides, requiring the downplaying of differences, secrecy, and often outright duplicity." Over the years, much of that diplomacy -- and on occasion, the duplicity -- fell not to a king or president, but to a single courtier: Bandar bin Sultan, the self-proclaimed "peasant prince."

Bandar was born in 1949, the son of a commoner and a powerful Saudi royal. While his 32 half-brothers and -sisters gallivanted around the palace grounds, Bandar played barefoot on the dirt road outside his mother's Riyadh home. At 17, he joined the Saudi Air Force, determined to prove himself to the world. He rose through the ranks, and in 1970 flew to Texas for additional training. Among his first sights was a group of Dallas Cowboys cheerleaders, whom he described as "magnificent." (Bandar eventually painted his private jet blue and silver.)

He returned to the States six years later, this time insinuating himself into the midst of a controversial arms deal that gave the Saudis advanced U.S. fighter jets. Bandar proved a particularly able diplomat, and by the late '70s he had become what Ottaway calls "the living embodiment of the U.S.-Saudi relationship." First as the king's personal envoy and then as ambassador to Washington from 1983 to 2005, he worked with five U.S. presidents and grew particularly close to the Bush family, a relationship pilloried by filmmaker Michael Moore in "Fahrenheit 9/11."

Ottaway, somewhat miraculously, pile-drives through all of this in about 300 pages. His source material is wide and varied: interviews with Bandar, declassified documents and the recollections of such Washington insiders as Colin Powell and Anthony Lake. On the one hand, it all adds up to a curiously dry piece of writing. (We're told, for instance, that Bandar is something of a latter-day Gatsby, but what we learn about his personal life could fit on a single page.) On the other hand, "The King's Messenger" is an incisive account of one of the most influential diplomats of the modern age. Bandar emerges as a tragic hero -- canny but hubristic; skilled yet ultimately unable to preserve the strength of the original bond between the United States and the House of Saud.

Matthew Shaer writes regularly about books for the Christian Science Monitor, where he is a staff reporter.